1. The Field of the Invention
The present invention relates to catheters. In more particular, the present invention relates to a drainage catheter hub having a welded suture and a stylet lumen in the sidewall of the drainage catheter tubing. The suture and stylet are adapted to secure a suture thread to maintain the anchor configuration of the distal end of the catheter in order to secure the position of the catheter within the patient's body.
2. The Relevant Technology
Drainage catheters are utilized to drain volumes of fluids that collect in a patient's tissue, body cavities, or other positions within a patient's body that exceed normal volumes. Collected fluids can contribute to infection, exert harmful pressure on the patient's organs, or otherwise impede with proper care and recovery of a patient. The drainage catheter is introduced into the patient to the site where the excess fluid is accumulated. A plurality of drainage bores are positioned in the distal end of the catheter to allow passage of the fluids from the volume of fluid to the lumen of the catheter.
FIG. 1 is a perspective view of a prior art drainage catheter tube 10. Distal end 14 of drainage catheter tube 10 is adapted to be positioned in a volume of fluid to be drained from a patient. In the illustrated embodiment, distal end 14 is curved to form an anchor configuration to secure the drainage catheter at the site where excess fluid is accumulated. Loop 16 comprises the anchor configuration formed in distal end 14. The configuration of loop 16 provides a reliable anchor even in the event that the tissue surrounding the drainage site does not provide a solid or reliable substrate to maintain the position of the catheter. Loop 16 is formed by curling distal end 14 of catheter tube 10 such that the tip of the catheter tube 10 contacts a more proximal position on catheter tube 10. Suture 18 is utilized to form loop 16 to anchor distal end 14 in a desired drainage position. Suture 18 runs the length of catheter tube 10 such that it extends from a proximal end of catheter tube 10. Because the proximal end of catheter tube 10 is configured to be positioned outside the patient, suture 18 allows a user to secure or release loop 16 once the distal end 14 of catheter tube 10 is positioned inside the patient.
A plurality of drainage bores 20 are formed on the inside diameter of loop 16. Drainage bores 20 allow fluid to flow from the volume of fluid in the body cavity to a lumen 22 of catheter tube 10. A stylet 24 is provided to selectively secure suture 18 such that suture 18 can be utilized to form loop 16. Loop 16 is formed by securing the tip of catheter tube 10 to a point on catheter tube 10 corresponding with a suture bore 23. Suture 18 runs the length of lumen 22, exits the tip of catheter tube 10, enters suture bore 23, and is wrapped around stylet 24. Stylet 24 is positioned in a stylet lumen 26 in catheter wall 28. Stylet lumen 26 and stylet 24 terminate at suture bore 23 adjacent the distal end 14. When suture 18 is provided with sufficient slack, distal end 14 of catheter tube 10 can be straightened for insertion or removal of distal end 14 to/from the patient. When suture 18 is foreshortened, the tip of catheter tube 10 is securely drawn to a position on catheter tube 10 corresponding with suture bore 23. When tip of catheter tube 10 is secured adjacent suture bore 23, loop 16 is formed.
Suture 18 is adapted to have a double length configuration along the length of lumen 22 such that both ends of suture 18 extend from the proximal end (not shown) of catheter tube 10. In other words, suture 18 is threaded distally along the length of lumen 22 of catheter tube 10, exits catheter tube 10, is wrapped around stylet 24, re-enters catheter tube 10, and is threaded back to the proximal end of the catheter tube 10. The user manipulates both ends of suture 18 to tighten or loosen the anchor configuration of distal end 14. To tighten the anchor configuration the user grasps both ends of suture 18 and pulls in a rearward direction. To loosen the anchor configuration of distal end 14, the user relaxes the tension on, or releases, both ends of suture 18. Because suture 18 secures distal end 14 while extending to the proximal end of catheter tube 10, the user can manipulate suture 18 to maintain or release the anchor configuration of the distal end 14 of the catheter tube 10 while the distal end 14 of the catheter tube 10 is positioned inside the patient. In one device one end of the suture is anchored relative to the catheter hub while the other end is free.
When the volume of fluid in the body cavity of the patient has been drained, the practitioner will release loop 16 such that catheter tube 10 is no longer anchored in the body cavity. By releasing loop 16, catheter tube 10 can be removed from the patient. The user can release loop 16 utilizing one, or both, of-suture 18 and stylet 24. To release loop 16 utilizing stylet 24, a user simply retracts stylet 24 in a rearward direction. Because suture 18 is secured to catheter tube 10 by stylet 24, once stylet 24 is retracted beyond suture bore 23, nothing is available to secure suture 18 to catheter tube 10. As a result, suture 18 is released and catheter tube 10 can be withdrawn from the patient.
The practitioner can also utilize suture 18 to release loop 16 and withdraw catheter tube 10 from the patient without retracting stylet 24. To release loop 16 utilizing suture 18, the user grasps only one of the two ends of suture 18 that is extended from the proximal end (not shown) of catheter tube 10. The user then pulls the end of suture 18 in a rearward direction. This pulls the free end of suture 18 into catheter tube 10. As the user continues to pull the end of suture 18 in a rearward direction, the free end of suture 18 travels the length of lumen 22, exits the tip of catheter tube 10, and is unwound from stylet 24. Once suture 18 is unwound from stylet 24 the tip of catheter tube 10 is no longer secured adjacent the proximal position on catheter tube 10 and loop 16 is released. The practitioner can utilize suture 18 in the event that stylet 24 becomes bound by tissue, is kinked, or otherwise becomes inoperable. The practitioner can also utilize the double length configuration of suture 18 to release loop 16 in drainage catheter designs that do not include a stylet.
One drawback presented by the double length configuration of suture 18 relates to the passage of fluids through drainage bores 20. In the illustrated embodiment, the double length of suture 18 is depicted as being positioned in the center of lumen 22 along the entire length of catheter tube 10. This positioning is provided to more clearly illustrate the double length configuration of suture 18. In practice, the tension on suture 18 utilized to maintain the configuration of loop 16 draws suture 18 against the inner diameter of lumen 22. This positions suture 18 across drainage bores 20 substantially reducing the effective cross-section of drainage bores 20. As a result, a lesser amount of volume is permitted to pass from the exterior of catheter tube 10 to lumen 22. Additionally, larger articles and materials such as clots, tissue, or other materials suspended in the fluid cannot be drained through the drainage bores. This not only makes drainage of fluids less efficient, it also increases the likelihood that the drainage bores 20 will be clogged by materials suspended in the fluid.
FIG. 1B illustrates a prior art drainage catheter tube 10a which overcomes some of the deficiencies presented by the design of drainage catheter tube 10 of FIG. 1A. In the illustrated embodiment, a suture 18 having a single length is provided in connection with drainage catheter tube 10a. Suture 18 does not extend to the tip of catheter tube 10a. Instead, suture 18 exits catheter wall 28 at a position proximal to the tip of catheter tube 10a. In contrast to catheter tube 10 of FIG. 1A, stylet 24a and stylet lumen 26a extend along the inside diameter of loop 16a to approximately the tip of catheter tube 10a. Suture 18 extends from an exit bore 29 positioned proximally on catheter tube 10a through catheter wall 28 and around stylet 24. Suture 18 is secured to stylet 24 by tying a knot in the distal end of suture 18. This allows the use of a single length design for suture 18 minimizing obstruction along the length of lumen 22. Because stylet 24a and stylet lumen 26a extend along the inside diameter of loop 16a, drainage bores 20a are positioned on the outside diameter of loop 16a. This permits drainage of fluid to lumen 22 through drainage bores 20a without obstruction from suture 18 or stylet 24a. 
While the design of drainage catheter tube 10a overcomes some of the deficiencies of catheter tube 10 of FIG. 1A, catheter tube 10a also has a number of deficiencies. For example, the knot formed in the distal end of suture 18 utilized to secure suture 18 to stylet 24a can be easily encrusted with clots, tissue, or other materials suspended in the fluid. This encrustation can lodge suture 18 within stylet lumen 26a such that when stylet 24a is removed, suture 18 and loop 16a are not released. This can be problematic, particularly where the practitioner is unaware that the anchor configuration of loop 16a has not been released and attempts to withdraw the catheter.
Another deficiency is presented by the positioning of drainage bores 20a on the outside diameter loop 16a. In some clinical settings, when the volume of fluid begins to drain, the positive pressure on the walls of the cavity in which drainage catheter tube 10a is positioned begins to decrease. This can result in shrinking of the size of the cavity. As the size of the cavity begins to shrink, the walls of the cavity contact the outside diameter of loop 16a. This can result in obstruction of drainage bores 20a directly by the walls of the cavity before the volume of fluid in the cavity is sufficiently drained. Where the practitioner relies on the volume of fluid being drained from the proximal end of the catheter as an indicator of the volume of fluid in the cavity, the practitioner may believe that no additional fluid is contained in the cavity. Additionally, the practitioner may be unaware of recurring fluid draining into the cavity that may otherwise be drained if not for blocking of the drainage bores 20a by the cavity wall. As a result, when the flow of fluid slows or stops prematurely in a particular procedure as a result of contact between the drainage bores 20a and the cavity walls, the practitioner may prematurely withdraw the drainage catheter tube 10a from the patient.